1664330981 has 2 divisors, whose sum is σ = 1664330982. Its totient is φ = 1664330980.

The previous prime is 1664330933. The next prime is 1664330989. The reversal of 1664330981 is 1890334661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1659340225 + 4990756 = 40735^2 + 2234^2 .

It is an emirp because it is prime and its reverse (1890334661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1664330981 - 2²² = 1660136677 is a prime.

It is a super-2 number, since 2×1664330981² = 5539995228632844722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664330989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832165490 + 832165491.

It is an arithmetic number, because the mean of its divisors is an integer number (832165491).

Almost surely, 2^1664330981 is an apocalyptic number.

It is an amenable number.

1664330981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664330981 is an equidigital number, since it uses as much as digits as its factorization.

1664330981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 41.

The square root of 1664330981 is about 40796.2128266828. The cubic root of 1664330981 is about 1185.0769902561.

The spelling of 1664330981 in words is "one billion, six hundred sixty-four million, three hundred thirty thousand, nine hundred eighty-one".